Exam Three - 2005

Exam Three - 2005 - Biology 310, Cell Biology Third Midterm...

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Biology 310, Cell Biology Third Midterm Examination Spring 2005 Name: [Print Clearly] _________ ________ Student Number ____________________ Name:[Signature] ___________________________ Write in INK . Examinations written in pencil or erasable ink will not be read and a failing grade will be assigned. DO NOT USE DIAGRAMS FOR ANY ANSWER. The value of each question is shown in parentheses. If your handwriting is poor, PRINT your answers. Illegible answers will not be read and will be given the score of zero. Use the back of the pages to write or print your answers if you do not have enough room on the front of the examination. Think before you write. Make your answers concise and correct. Ask yourself what the question is really asking. Take your time; we will use the entire 2 ½ hours for the exam, even though it is written as a 80 minute exam. 1. What molecules are released from mitochondria during apoptosis? List them and indicate their functions Use the following table. Be neat and organized. [10] Molecule Function 1. 2. Endoplasmic reticulum stress, caused by miss-folded or unfolded proteins, can lead to apoptosis. One response to this stress is the release of Calcium from the ER. How would Calcium promote apoptosis? [2] [One two sentences] 3. Within an hour after cell damage P53 moves to the mitochondria and binds Bcl-2 and Bcl-X L. a. Is cell death promoted or inhibited and why ? [3] 4. Damaged cells of the lesser quail showed the following characteristics: Phosphatidylserine on the outer leaflet of cell membranes, active ATP activity, low NAD+ activity and little PARP [poly{ADP ribose}polymerase] activity. Will these cells die by necrosis or apoptosis? [1] -1- 5. A mutant of the red-crested twit has several unusual characteristics. It has a very short life span and ages very rapidly. A former student of Biology 310, now an eminent expert in twits, noted that cells of the mutant twit: 1. fail to undergo apoptosis when receiving “death” signals 2 . Have a very active cellular metabolism, 3. Exhibit over-expression of the BH sub-group of the Bcl-2 family, specifically Bcl-2 and Bcl-X L , and 4. Hexokinase is firmly attached to the mitochondria. 5. Telomeres of the cells are short and telomerase activity is absent. Based on this data and your knowledge of cell biology, answer the following questions.
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a. What is/are the role[s] of the BH sub-group of the Bcl-2 family? [2] b. In these mutant cells is hexokinase preventing or promoting apoptosis? [1] c. Based on your answer to 5b above, what is/are the role[s] of hexokinase? [2] d. Based on the data above , why do the cells age rapidly? [4] . e. Would these cells be expected to exhibit an increase or a decrease in ROS [reactive oxygen species] ? _________ _____________ [1] Why? [2] 6. A culture of porcine kidney cells stopped dividing and showed the following characteristics: telomere shortening, loss of telomerase activity, loss of DNA repair mechanisms, and loss of chromatin silencing, a. Are
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Exam Three - 2005 - Biology 310, Cell Biology Third Midterm...

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